The technical challenges of forming a mask pattern may be influenced by the requirement of precision of a pattern formed on a semiconductor substrate. If an optical proximity effect (OPE) of a mask pattern is not adequately taken into consideration, a line width of a mask pattern may be distorted. If a line width of a mask pattern is distorted, the linearity of the line width may become short. Distortions in line width may influence characteristics of a semiconductor device.
Photolithography technology may cope with mask design sensitivities to adjust the quantity of light transmitted to a mask. Photolithography maybe essential in manufacturing some semiconductor devices. Photolithography may be performed by uniformly applying a photo resist layer on a wafer, exposing the applied photo resist layer using a photo mask (which may have a predetermined layout), and/or developing the exposed photo resist layer to from a specific pattern.
Since some semiconductor devices may have high-density integration, a design rule may have a fine scale. In a photolithography process, the optical proximity effect (OPE) between neighboring patterns may cause defects. If a quadrilateral pattern is formed, various phenomenons caused by OPE may occur. Examples of phenomenons are: a corner rounding phenomenon in which corners of the quadrilateral pattern are rounded by diffraction of light and/or a phenomenon in which sparsely collected patterns in a region (e.g. an isolated region) are patterned to have a small size compared to patterns in a densely collected region.
Examples of methods capable of minimizing distortion of light caused by patterns formed on a mask may include optical proximity correction (OPC) technology and phase shifting mask technology. Optical proximity correction may correct diffraction of light using a pattern. Phase shifting mask technology may increase optical contrast and resolution.
Various methods are used in OPC technology. A rule based OPC method may change a correction value into a rule according to an arbitrary reference and perform pattern correction based on a rule. A model based OPC method may predict a completed shape on a wafer, which has passed through a mask process, a lithography process, and/or an etching process. A model based OPC may predict based on types of various patterns and build a model library. A model based OPC may check performance results through optical rule checking (ORC) after application of a model library and calculating a correction value. There may be methods which combine a rule based OPC method and a model based OPC method.
Mask data processing (MDP) may make up a mask pattern different from a design pattern such that the final completion dimensions has design pattern dimensions that consider a conversion difference between respective processes of forming a pattern that may be important. MDP may include changing a mask pattern by a figure operation, a design rule checker (DRC), an OPC for correcting an OPE after the MDP, and/or another similar method. These processing methods maybe performed so that a mask pattern is properly corrected and/or the final completion dimensions reach a desired dimension.
FIG. 1 illustrates a flow of forming a mask pattern using a model based OPC method. As illustrated in FIG. 1, a database for a design pattern (S10) may be subjected to design verification with a DRC (S20). Mask data preparation (MDP) may change a mask pattern (S30). An OPC may correct an OPE (S40). The results of an OPC may be checked through ORC and may be corrected (S50). If correction is required more than one time, an OPC environment including various parameters may be adjusted and an OPC may be performed again (S60). If correction is not required again, pattern generation may be performed (S70). Data may then be sent to a mask shop (S80).
The flow of forming a mask pattern using a model based OPC method may have difficulty in predicting all layout patterns diversified with the lapse of time, no matter how many test patterns may be used to form a model pattern. A model based OPC method may be limited to building and application of a model library. In some circumstances, an OPC may not be entirely effective. In a process of forming a mask pattern, a pattern may be corrected again after an ORC. An OPC environment may include various parameters that may be adjusted and then the OPC may be performed. In some circumstances, process time may be relatively long, process failure may be caused by manually performing an OPC directly multiple times, and/or a pattern bridge phenomenon may occur.